Wayanad landslides: Kerala mulls next-gen sequencing as lack of clean DNA a challenge in identification
Revenue Minister K Rajan said the government had initiated talks to make use of NGS in the identification of such samples where extraction of clean DNA has been difficult.
Revenue Minister K Rajan said the government had initiated talks to make use of NGS in the identification of such samples where extraction of clean DNA has been difficult.
Revenue Minister K Rajan said the government had initiated talks to make use of NGS in the identification of such samples where extraction of clean DNA has been difficult.
The state government is mulling the use of advanced next-generation DNA sequencing technology (NGS) to see if it could help in identifying 52 decomposed samples at the Regional Forensic Lab in Kannur where a marathon identification process of the Wayanad landslide victims is being carried out by a six-member team.
While the team has identified the gender of 248 samples through DNA profiling, the lack of clean DNA, especially from decayed samples has hindered the identification process. They have enlisted 52 such samples and, according to sources, 20 more samples in a highly putrefied state have also arrived at the laboratory. Soft tissue samples that are easily prone to accelerated decay have been challenging for the team.
Revenue Minister K Rajan said the government had initiated talks to make use of NGS in the identification of such samples where extraction of clean DNA has been difficult.
"We want to use every possible technology to identify the victims and have held talks with experts in the field to see if identification can be made out of putrefied samples,’’ said Rajan. NGS sequencing facilities are available at RGCB, Thiruvananthapuram, and ICMR-NIV field unit Alappuzha in Kerala.
Short tandem repeat analysis (STR) is done for DNA profiling. Unlike the present technology for STR analysis, NGS is faster and more accurate, is likely to provide a more comprehensive view of the human genome, and can do simultaneous sequencing of DNA fragments. It also requires lower sample input.
"The minimum DNA quantity required in traditional analysis method is 1nanogram. With some of the samples, we are unable to get the required quantity for amplification. We do repeat analysis in such cases to check if we can extract some results. NGS is expected to provide higher sensitivity results even with a lower input. So far, this has not been used in Kerala for disaster victim identification (DVI) and it remains to be seen if NGS can be helpful,’’ an official said.
Sam Santosh, strategic advisor for the Kerala Genome Data Center (KGDC) which focuses on Genomics leveraging NGS Technologies, said NGS will be helpful in identification even in the case of decomposed samples. "There may be the case of contamination, but we have the technology to address such concerns. It has been used in individual cases earlier," he said.
It is learnt that while the gender of 248 samples has been identified, the team has established an identity (with names) by cross-matching with reference samples in 42 cases. This needs to be finalised. Bone samples have aided identification in such cases. Fifty-four samples were profiled from 154 body parts. The forensic lab team has been working non-stop to build profiles out of over 442 samples in the past two weeks.
Rajan said the cross-matching will now start for 118 missing persons with the DNA profile built from 401 samples. "Ninety-one blood samples of relatives are available for cross-matching. In three cases, close relatives will arrive from other states for collection of samples," he said.
Cross-matching also has challenges. There are cases where close relatives are also dead and in some cases, samples of spouses have been collected instead of father/mother. Such cases have to be sorted for a fresh collection of samples so that accurate cross-matching can be done with DNA profiles.